The present invention relates to a semiconductor device packaged by mounting semiconductor chips over a mounting board, and a method for manufacturing the semiconductor device.
With greater functioning and miniaturization of small-sized electronic equipment typified by a cellular phone or the like, there has recently been an increasingly demand for a semiconductor device, a so-called SiP (System in Package) packaged by mounting a plurality of semiconductor chips and chip parts such as passive elements over a mounting board called an interposer in high density.
However, there is a need to make the mounting board as small in size as possible for the purpose of high-density packaging. A reduction in the difference between the outer shape of the mounted semiconductor chip and the outer shape of the mounting board is required.
The space between the mounting board and the semiconductor chip is normally sealed with a sealing resin called underfill. However, a problem arises in that when the difference between the outer shape of the semiconductor chip and the outer shape of the mounting board is made small, the sealing resin covers external terminals provided around a chip mounting area of the mounting board due to an overflow of the sealing resin, thereby causing a poor connection.
Although a reduction in its overflow can be improved by adaptation of a high-viscosity sealing resin, its filling needs a long period of time and voids and unfilling are easy to occur.
There has thus been proposed in a patent document 1 (Japanese Unexamined Patent Publication No. 2005-276879), an example in which a sealing resin low in viscosity and good in filling property is applied and a dam for damming the sealing resin is provided between a semiconductor chip and each external terminal over a mounting board such that the extruded sealing resin does not cover the external terminals provided around a chip mounting area of the mounting board.
However, the present situation is that the above proposal adopts a technique for applying the resin over the entire surface of the mounting board for dam formation and thereafter processing it into a predetermined shape in accordance with a photolitho process and cannot obtain satisfaction in terms of cost, manufacturing time and the like.